The near-inertial internal wave energy distribution is investigated in the southwestern Japan/East Sea using vertical round-trip travel time of sound (τ) data from 23 pressure-sensor-equipped inverted echo sounders (PIESs) and data from Aanderaa recording current meters (CMs). Currents associated with low-mode near-inertial internal waves are slightly inclined and displace the thermocline vertically, which can be detected in τ. The band-pass filtered τ records exhibit high near-inertial energy distributions that vary interannually with changes observed in mesoscale circulation. An explanation for this is offered as trapping of near-inertial energy in anticyclonic regions, which is supported by scatterplots of monthly-rms band-pass filtered τ at inertial frequency bands vs. monthly-mean relative vorticity. The spectra from all but one deep CM exhibit a blue shift, consistent with the equatorward propagation of near-inertial waves. The exception has the highest near-inertial wave energy, and is located near the center of a warm anticyclonic eddy.